Simulate POV Walking Camera
An effect like this can indeed be obtained with the Cycles modifier:

(green curve: linear forward (Y+) motion; blue curve: oscillating up-and-down motion with a net downwards (Z-) displacement over time)
Just edit your basic step making sure that its first and last keyframe are offset (vertically) from each other, then set the Cycles modifier setting &quot;After:&quot; to &quot;Repeat with offset&quot;.

A limitation of this method is that you can't easily change the steepness of the hill over time.
If you want more control
If you want more control over the velocity, the steepness, etc, you can use a different method. You will need two objects: your Camera and an Empty.

Assign the &quot;walking&quot; motion (just up and down, no net displacement) to the the camera (as you've already done)
keyframe the Empty so that it follows the profile of the hill at the desired pace
Place them on the same position at frame 0, then select the camera and the empty (order matters!) and parent the former to the latter using Ctrl+P &gt; &quot;Set Parent to: Object&quot;.